Luigi first appeared in Mario Bros. as player 2 and was a recolor of mario with no new actions. In Super Mario Bros., he still is a second player's character, still a pallette swap. He got his first true playable experience in Super Mario Bros. 2, where he accompanied Mario, Toad, and Princess Peach to the land of Subcon, where he first showed off his exellent jumping abilitys. In Super Mario Bros. 3 and Super Mario World, Luigi was (again) a pallete swap, and again, had no new moves until remakes such as Super Mario All-Stars featuring super mario world. In Super Mario World 2: Yoshi's Island, Baby Luigi was kidnapped by Kamek and his Toadies, under the orders of Baby Bowser, probably as bait to catch baby mario. Baby Mario and Yoshi had to rescue him from Bowser's clutches.
Mario is Missing
In this NES, SNES and PC title, Luigi broke into Bowser's Castle with Yoshi to save his missing brother Mario. It was an educational game that made you learn about history. It has been surmised by some that this was an attempt by Nintendo to get younger kids involved in the Mario franchise, perhaps so Nintendo could make more money. In the NES and SNES, Luigi looks like Mario and is the same size as Mario. The gameplay in the SNES version is VERY different, where luigi and yoshi must Travel to Bowser's castle. The visual appearance of his character in this game made him quickly become an internet 'meme'.
Luigi got his first major role in Luigi's Mansion. In that game Luigi had to save his brother, Mario, from a mysterious mansion filled with ghosts and Boos. Luigi also helped Professor E. Gadd in capturing a group of super evil, super powerful portrait ghosts, with the help of a vacuum cleaner, named the Poltergust 3000 by E. Gadd. Luigi defeated King Boo and a giant possessed Bowser and freed his older brother, Mario.
Super Smash Bros. series
Luigi has appeared in all three Super Smash Bros. series as a secret unlockable character. In Super Smash Bros. Brawl, Luigi got his own stage, Luigi's Mansion. His final smash is the Negative Zone, where he does a dance and creates an energy field that causes random havoc on any character caught in it and turns most everything into negative colors. In SSB and Melee, Luigi's voice is only a sped up version of Mario's, while in Brawl, he has his own voice.
The Mario Party Series
Luigi has been playable since his debut in the original Mario Party. Like most playable characters in Mario Party, Luigi got his own board, Luigi's Engine Room.
Mario Kart Series
Luigi has been in every Mario Kart game. He has been middleweight. He has always been one of the speedy Characters, like Mario. Luigi has had many tracks named after him, such as the Nintendo 64 Luigi Circuit, the GameCube Luigi Circuit, the Game Boy Advance Luigi Circuit, the DS Luigi's Mansion, and the Wii Luigi Circuit. In Mario Kart: Double Dash, Luigi's special item was the green fireball.
New Super Mario Bros.
Luigi is a playable character. When you go to the save file, press left, right and A at the same time. You will then be able to play as Luigi.
In New Super Mario Bros. Wii, Luigi can be played as by the second, third, or fourth player. He is also the Super Guide, in which after losing eight times, a green block will appear the ninth time you play that level, and if Mario hits it, Luigi will show Mario how to finish the level basically, as in he won't get all the star coins or show the player the secret places.
Super Mario Galaxy 2
If the player collects 20 Power Stars, then Luigi will appear at the start of certain galaxies. If you talk to him, the player can play as Luigi. And after you win the level with him, a message will pop up saying a ghost has appeared in that galaxy, and if the player goes back to that galaxy, then the player can play as Luigi in the game. At the end of the game you can go back and play as Luigi at anytime by going to a room with a green 'L' ('M' if you are Luigi) and enter you will pop up again as the brother who's initial was on the the room. (Note: When you go back to Starship Mario after completing the game the Mailtoad will have a letter from Luigi if you are Luigi you will still recieve the letter but the Toad will mention that you are Luigi and ask why you sent a letter to yourself, This doesn't happen if you are Mario.)
Luigi's Mansion 2
Luigi appeares in Luigi's Mansion 2 as the hero. He is using the Poltergust 5000 created by Professer E. Gadd to suck up more ghosts. The gameplay is similar to it's predessor Luigi's Mansion for the Nintendo GameCube.
Powers and Abilities
Superhuman Strength: Luigi is able to lift and press objects that are several times his own weight, but not as much as Mario can. The exact upper limits of his strength are that it is great, but not as great as Mario's. In Super Mario 64 DS, Luigi can lift King Bob-Omb. An even more impressive feat is during the fight with Bowser. Luigi can lift him by the tail, spin him around and then throw him, but not as effectively as Mario. Luigi spins Bowser around faster and farther with more spins. Luigi's incredible strength also extends to his legs, allowing him to perform his signature move, the Jump. Luigi is extremely good at jumping, and is capable of leaping two stories high. He is the best jumper in the Mushroom Kingdom, even better than Mario.
Superhuman Durability: Luigi has a significant level of durability. He can withstand great impacts, such as falling from a height of several stories or being struck by an opponent with superhuman strength. Luigi can also endure extreme environments, such as volcanoes and tundras. Also, he can withstand fire, electricity and ice.
Superhuman Stamina: Luigi can maintain continuous physical activity for an indefinite period of time.
Pyrokinesis: Luigi has the ability to create and manipulate fire. This ability changes throughout the games he has appeared. In the platform games, such as Super Mario Bros., Luigi needs a Fire Flower to gain pyrokinesis. But in the RPGs and Super Smash Bros. series, Luigi already has this power. Luigi is quite good at using fire, like Mario is.
Lightning: Luigi has the power to mold lightning in his hand into a sphere, creating a powerful attack, called the Thunderhand, that can shock and damage enemies quite severely.